Tactical nuclear weapons produce high intensity Prompt Initial Radiation (PIR) which consists of gamma rays and fast neutrons. This PIR is followed in time by gamma rays from the radioactive fallout. The environment of strategic nuclear weapons is quite different, because in that case the radius of total destruction by blast and shock is larger than the range of the PIR. Thus, if we concentrate only on radiation from strategic nuclear weapons, only fallout is important.
These circumstances determine the main operational requirements for an all purpose miniaturized radiation meter (radiac) for use by soldiers on a tactical nuclear battlefield. These requirements are:
(A) The gamma ray and fast neutron doses should be measured and displayed separately within the range of 0.01 to 10 Gray (tissue) when delivered at dose rates between 3.times.10.sup.-9 Gray per second and 10.sup.10 Gray per second. The required accuracy is plus or minus 20 percent or plus or minus 0.2 Gray, whichever is greater. PA1 (B) The ambient dose rate (of gamma rays only) should be measured in real time within the limits of 3.times.10.sup.-9 Gray per second and 3.times.10.sup.-1 Gray per second with an accuracy of plus or minus 20 percent. PA1 (C) The instrument should respond to fast neutrons and to gamma rays of quantum energies above 80 keV.
A practical radiac would have to meet these requirements and be small, lightweight, rugged, relatively inexpensive, and consume a minimum amount of power. Those concerned with the development of such radiacs have long recognized the need to address these and other related problems.
It is an object of the invention to provide a combination gamma ray and neutron dosimeter.
It is another object of the invention to provide a small, lightweight, rugged, relatively inexpensive radiac for the tactical nuclear battlefield which can operate on a minimum amount of power.
It is another object of the invention to provide a technique of analyzing the output of radiation detectors to determine the amount of gamma and fast neutron radiation absorbed within the detector material.